Foothill College, located near San Francisco, has this great series of regular talks called the Silicon Valley Astronomy Lecture Series. They invite all manners of astronomer there to give the public-level talks, and the topics are wide ranging. Some of these talks are now online as audio (and some video) podcasts! You can hear professional astronomers at the tops of their games, talking about Jupiter, asteroids, dark energy, and even alien life. They'll be adding more talks as time goes on, too. I gave a lecture there years ago, but it wouldn't translate well into audio; I put too many sight gags in my slides. But maybe they'll have more video with time, too...